“However, our results clearly demonstrate that mosasaurs underwent the same kind of evolution as did the earlier ichthyosaurs and later whales -- that is, they gradually attained a streamlined body powered by a semiluminate tail fluke. This, in turn, suggests that at least the derived forms were pursuit predators and capable of high-speed swimming over long distances.”
Textbook illustrations of mosasaurs will likely change as a result of this latest research, since earlier drawings made them look more like eels or underwater snakes.
Students might also pay more attention to them in future, since researchers now have such a good fossil record for mosasaur evolution, with nearly every step documented. It’s a bit like looking at a hefty 1920s touring car and then seeing it gradually evolve into a streamlined speed machine.
Being at the top of the food chain, large mosasaurs “were capable of handling virtually anything that came in their way.”
Whales emerged later, so they weren’t a threat. Evidence suggests mosasaurs did battle with sharks, however.
Frank O’Keefe, a Marshall University biologist, has also studied prehistoric marine life.
O’Keefe told Discovery News that the mosasaur ecosystem, aside from sharks, included plesiosaurs (another large now-extinct marine reptile), fish, squid, ammonites and other invertebrates. Mosasaurs might have also encountered toothed birds and pterodactyls, which often hung out near water, hoping for vulnerable prey.
O’Keefe said both plesiosaurs and mosasaurs went extinct about 66 million years ago, when dinosaurs also died out.
It is possible that mosasaurs dined on dinosaurs, but the meal likely would not have been tasty, or fresh.
“Dinosaurs lived on land," Lindgren said, "so the only chance of a mosasaur ever getting a bite out of one of those reptiles would have been a bloated and floating carcass that somehow ended up at sea.”